libpcap: drop libnl headers patch

libpcap: drop libnl headers patch

We can avoid host headers using a --with-libnl parameter to override the
default host headers path. The configure script adds /include suffix to the
include path. So we still need to manually add -I with the correct path to
CFLAGS because libnl headers are under the libnl3/ directory.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>